27,446 research outputs found
Design and commissioning of a timestamp-based data acquisition system for the DRAGON recoil mass separator
The DRAGON recoil mass separator at TRIUMF exists to study radiative proton
and alpha capture reactions, which are important in a variety of astrophysical
scenarios. DRAGON experiments require a data acquisition system that can be
triggered on either reaction product ( ray or heavy ion), with the
additional requirement of being able to promptly recognize coincidence events
in an online environment. To this end, we have designed and implemented a new
data acquisition system for DRAGON which consists of two independently
triggered readouts. Events from both systems are recorded with timestamps from
a MHz clock that are used to tag coincidences in the earliest possible
stage of the data analysis. Here we report on the design, implementation, and
commissioning of the new DRAGON data acquisition system, including the
hardware, trigger logic, coincidence reconstruction algorithm, and live time
considerations. We also discuss the results of an experiment commissioning the
new system, which measured the strength of the
keV resonance in the NeNa radiative proton
capture reaction.Comment: 11 pages, 7 figures, accepted for publication in EPJ A "tools for
experiment and theory
A New Approach to Axial Vector Model Calculations II
We further develop the new approach, proposed in part I (hep-th/9807072), to
computing the heat kernel associated with a Fermion coupled to vector and axial
vector fields. We first use the path integral representation obtained for the
heat kernel trace in a vector-axialvector background to derive a Bern-Kosower
type master formula for the one-loop amplitude with vectors and
axialvectors, valid in any even spacetime dimension. For the massless case we
then generalize this approach to the full off-diagonal heat kernel. In the D=4
case the SO(4) structure of the theory can be broken down to by use of the 't Hooft symbols. Various techniques for explicitly
evaluating the spin part of the path integral are developed and compared. We
also extend the method to external fermions, and to the inclusion of isospin.
On the field theory side, we obtain an extension of the second order formalism
for fermion QED to an abelian vector-axialvector theory.Comment: Sequel to hep-th/9807072, references added, some clarifications and
corrections, 29 pages, RevTex, 8 diagrams using epsfig.st
Static and dynamic deflection studies of the SRM aft case-nozzle joint
The redesign of the joints on the solid rocket motor (SRM) has prompted the need for analyzing the behavior of the joints using several different types of analyses. The types of analyses performed include modal analysis, static analysis, transient response analysis, and base driving response analysis. The forces used in these analyses to drive the mathematical model include SRM internal chamber pressure, nozzle blowout and side forces, shuttle vehicle lift-off dynamics, SRM pressure transient rise curve, gimbal forces and moments, actuator gimbal loads, and vertical and radial bolt preloads. The math model represented the SRM from the aft base tangent point (1,823.95 in) all the way back to the nozzle, where a simplified, tuned nozzle model was attached. The new design used the radial bolts as an additional feature to reduce the gap opening at the aft dome/nozzle fixed housing interface
Letter to the Editor. Re: single potential analysis of cavernous electrical activity in spinal cord injury patients.
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